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State-Funded Cleanup of Former Service Station on Reservation Land
Enhanced Aerobic Biodegradation and In Situ Chemical Oxidation Provides Safe Approach to Remediate TPH-g and BTEX
Project Highlights
- Extensive coordination was required between state-funded Pollution Liability Insurance Agency (PILA) of Washington and US EPA Region 10
- Combined remedy approach using ORC Advanced® and PersulfOx® provided a safe solution for land used to raise livestock
Project Summary
The site located in Wapato, Washington is a former gas station situated on Reservation Land with historical releases dating back >20 years. The site is regulated through US EPA Region 10 and was previously an empty lot used for ranging cattle.
Initial remedial activities included excavation of source-area soil, however persistent contamination remained. Concerns were raised regarding how amendments might affect livestock. As a result, the remediation approach needed to be environmentally benign. The revised remedial plan included Enhanced Aerobic Biodegradation (ORC Advanced) and In Situ Chemical Oxidation (PersulfOx) to reduce the remaining concentrations and meet regulatory goals.
Technology Description
PersulfOx is a chemical oxidant that rapidly reduces the mass of the contaminants. This chemical consists of 90% sodium persulfate and 10% catalyst powder. PersulfOx is very effective in rapid oxidation of petroleum hydrocarbons in both soil and groundwater.
ORC Advanced is an engineered, oxygen release compound designed specifically for enhanced, in situ aerobic bioremediation of petroleum hydrocarbons in groundwater and saturated soils.
Results
An integrated treatment strategy was devised, which included injections in three separate areas. Two areas were treated with PersulfOx and ORC Advanced. The third area was treated with ORC Advanced only.
The by-products of ORC Advanced and PersulfOx are both insoluble and non-toxic, making the application safe and effective. Consequently, there were no issues relating to the landowner’s concern for amendments affecting livestock. A total area of 4,100 ft2 was treated for high levels of BTEX and TPH-g. Monitoring is ongoing.
LNAPL Remediation in a Chalk Aquifer under a Residential Property
with BRD Environmental Ltd
Introduction
After completion of the redevelopment of former industrial land into residential properties, significant Total Petroleum Hydrocarbon (TPH) contamination was discovered in the groundwater and smear zone under the gardens and parking area. The TPH comprised diesel and heating oil, with up to 40mm of Light Non- Aqueous Phase Liquid (LNAPL) evident in the monitoring wells.
The original source of contamination (an above-ground storage tank) was removed during redevelopment; however, residual contamination had migrated into a lower chalk aquifer and after the discovery of LNAPL present within chalk fissures above the water table, remedial action was required.
Figure. 1 On site RegenOx® injections using a direct push injection rig
Figure. 2 Total TPH Concentration in Boreholes BH13 and BH14
Method
The two most highly contaminated boreholes, BH13 and BH14, were located in a back garden and a car parking space. As space was restricted and to minimise the impact of works on residents, an in situ remedial technique was deemed the only viable option.
RegenOx® is an In Situ Chemical Oxidation (ISCO) reagent capable of treating high concentrations of a broad range of soil and groundwater contaminants including both petroleum hydrocarbons and chlorinated solvents.
The alkaline nature of RegenOx enabled its use within the chalk aquifer without adverse matrix reaction.
The ability of RegenOx to deal with both LNAPL and dissolved phase contamination avoided the use of ‘pump and treat’ equipment onsite. This minimised both operational and disposal costs and negated the requirement for bulky equipment on the site. Applications were completed using a small direct- push injection rig (Figure 1). This meant that the resident’s parking area could be reinstated at the end of each working day, so that they could park overnight as usual.
The RegenOx injections were completed in three events at two week intervals during June and July.
Results
A 99% reduction of TPH concentrations occurred rapidly in boreholes BH13 and BH14 following the injection works, with LNAPL no longer observed on the site.
Conclusion
A short campaign of RegenOx applications at the site completely removed any LNAPL and reduced TPH concentrations by 99% in a chalk aquifer and regulatory closure was achieved within a short period.
At £55,000 for the product and application work, the project was extremely cost effective, avoiding the use of operational and disposal costs on the site. The in situ nature of the works avoided disturbing or inconveniencing residents living on the site.
ISCO and Bioremediation at Former Petrol Station, Pays de la Loire, France
Under a former petrol filling station in the Loire Valley, in France the soil and groundwater was found to be contaminated with petroleum hydrocarbons (primarily BTEX). An integrated in-situ remedial solution has been put in place by a specialist remediation contractor, consisting of 26 PersulfOx injections in the source zone for fast and effective treatment of the most impacted soils and groundwater. ORC Advanced was also applied in the source zone to achieve long term in-situ bioremediation of any remaining petroleum hydrocarbons. In addition, an ORC Advanced barrier has been installed in the downstream plume area, to prevent off-site migration of the contamination.Read More
Enhanced Reductive Dechlorination Showing Positive Returns at Indiana Dry Cleaning Site
Project Highlights
- Combined remedies approach using an Enhanced Reductive Dechlorination (ERD) process successfully remediated an Indiana drycleaning site
- ERD process chosen eliminates need for long-term monitoring
- Contaminant concentrations reduced from thousands of μg/L pre-injection to single digits one month post-injection
2m 38s reading time
Project Summary
While the surrounding Mooresville, Indiana community applauds Crest Cleaners for proactively cleaning up a previously unidentified hazardous mess that was left behind from historic dry cleaning practices, the workhorses remediating the contamination are grinding away below the subsurface. Tiny microorganisms are destroying the PCE in the groundwater and reducing the concentration of the contaminant. It’s all a part of the “Enhanced Reductive Dechlorination,” (ERD) process, which is the primary approach of the Remedial Work Plan (RWP) being implemented by EnviroForensics®.
In addition to the potential for human health risks at the site as a result of soil or groundwater exposure, the contaminant plume in the groundwater represented a potential vapor intrusion risk to an offsite building. The project team debated between two viable options:
- Install, monitor, and maintain a Sub-Slab Depressurization System (SSDS) at the offsite location to mitigate the potentially harmful vapors underneath the building, which would have required years of maintenance and groundwater sampling; or
- Implement an ERD application to reduce the concentration of the groundwater plume, and eliminate potential vapor intrusion issues.
Based on the overall benefit to the community and to reduce stress and aggravation to adjacent property owners that comes with long-term monitoring, the project team chose option two.
Here’s how the remediation at this site worked. Naturally occurring bacteria called Dehalococcoides ethanogenes (DHC) are in the groundwater completing a process called reductive dechlorination where the chlorine atoms are cleaved off and replaced by hydrogen atoms. This process continues until the resulting compound is no longer dangerous. At this site, the process was occurring, but not at a rate that would make the cleanup cost-effective for the client.
In order to complete this cleanup we utilized a process called bioaugmented enhanced reductive dechlorination (ERD) and in situ chemical reduction (ISCR). The process begins by sampling the groundwater across the remediation area for contaminant concentrations and geochemical parameters including DHC populations to determine the dosage of injected materials required in each area of the site. Different areas received modified doses of materials based on the calculations completed by EnviroForensic’s geochemist.
The ERD agent, 3-D-Microemulsion® (3DMe®) was injected along with Chemical Reducing Solution (CRS®), an ISCR augmentation. The ISCR agent delivers a source of ferrous iron, designed to precipitate as reduced iron minerals and provide an additional abiotic pathway for the destruction of PCE. The two work synergistically, increasing the cost effectiveness of the injection. The pre-sampling of DHC revealed that the population of DHC needed to be augmented. 10 gallons of BDI® Plus (DHC enhanced fluid) was injected at each of the 92 injection locations used for the ERD/ISCR. The combination of these three injected materials allows for minimal site disturbance and a high level of effectiveness for the cleanup of drycleaning solvents.
An often overlooked byproduct of the ERD process is methane. As a preventative measure, the field staff upgraded the site building SSDS with an intrinsically-safe fan and installed an intrinsically-safe SSDS at the offsite building as an interim measure. Soil gas points were also BDI Plus is an enriched natural microbial consortium containing species of Dehalococcoides sp. (DHC). This microbial consortium has since been enriched to increase its ability to rapidly dechlorinate contaminants during in situ bioremediation processes. Chemical Reducing Solution is an iron-based amendment for in situ chemical reduction (ISCR) of halogenated hydrocarbon contaminants such as chlorinated ethenes and ethanes. installed between the injection areas and the adjoining properties to the east. Additionally, extra intrinsically-safe fans and piping are ready to be installed.
Technology Description
3-D Microemulsion is an engineered electron donor material that offers a novel 3-stage electron donor release profile, pH neutral chemistry, and is delivered on-site as a factory emulsified product.
BDI Plus is an enriched natural microbial consortium containing species of Dehalococcoides sp. (DHC). This microbial consortium has since been enriched to increase its ability to rapidly dechlorinate contaminants during in situ bioremediation processes.
Chemical Reducing Solution is an iron-based amendment for in situ chemical reduction (ISCR) of halogenated hydrocarbon contaminants such as chlorinated ethenes and ethanes.
Results
The results from the first injection event were very promising. Groundwater contaminant concentration went down from thousands of μg/L pre-injection to single digits μg/L one month post-injection. Quarterly groundwater sampling will continue for a year or two to demonstrate that the contaminant plume is retreating or remediated. The ultimate goal of the ERD approach is to reach site closure quickly, and reduce the costs and health risks of this contamination.
Remediation of PHCs and VOCs at a Former Dry Cleaner Site Using RegenOx®, ORC Advanced®, and ORC® Filter Socks
Former Dry Cleaning Site Redeveloped to Serve as New Home to Non-Profit Serving Homeless in Chilliwack B.C. Area
Project Highlights
- Introduction of RegenOx® and ORC Advanced® following in situ treatment using PulseOx1 resulted in the reduction in the initial concentrations of PHCs and dry cleaning chemicals in a sand and gravel aquifer, meeting site remediation goals
- Upon completion of remedial efforts, the project was awarded three British Columbia Ministry Environment instruments
Project Summary
A building occupied by a former dry cleaning business (1960s) located in Chilliwack, British Columbia was acquired by Ruth & Naomi’s Mission, (www.ranmission.ca) a non-profit organization serving Chilliwack. Environmental investigations to support the redevelopment of the former dry cleaner building revealed contamination of the soil and groundwater beneath the site and the offsite alley with petroleum hydrocarbons (PHCs) and dry cleaning related chemicals. Since the remedial excavation onto the offsite alley was not considered to be practical, RegenOx, along with ORC Advanced, was utilized for the in situ treatment of soil and groundwater within the excavation to reduce the remaining PHC and dry cleaning chemical concentrations.
Following treatment with RegenOx, reduction in the concentrations of PHC and dry cleaning related compounds were observed in soil and groundwater samples. RegenOx was additionally injected within the alley to treat the offsite plume. As a result, all post-remediation concentrations are below the applicable commercial land use standards. Additionally, ORC socks were applied to assist natural attenuation of any residual contaminants in groundwater. The successful investigation and remedial effort received three British Columbia Ministry of Environment instruments and now safely serves as a resource center and shelter.
Concentrations
- Volatile Petroleum Hydrocarbons VPH (up to 3,400mg/kg)
- EPH10-19 (8,200 mg/kg)
- Ethylbenzene (33mg/kg)
- Total Xylenes (160 mg/kg)
- Perchloroethylene (7μg/g)
- Trichloroethylene (2.8 mg/kg)
- VPHw (110mg/L)
- LEPH (5.6 mg/L)
- Ethylbenzene (2.14 mg/L)
- Toluene (2.7mg/L)
- Naphthalene (410μg/L)
- Perchloroethylene (2.76 mg/L)
- Xylenes (6.78mg/L)
- Vinyl Chloride (349 μg/L)
Technology Description
RegenOx is a percarbonate-based in situ chemical oxidation technology that rapidly destroys petroleum hydrocarbons and chlorinated contaminants through powerful chemical reactions. It directly oxidizes contaminants while a catalytic component generates oxidizing free radicals to destroy the target compounds.
ORC Advanced is a proprietary formulation of food-grade, calcium oxy-hydroxide that produces a controlled release of molecular oxygen to enhance aerobic biodegredation.
ORC Filter Sock is a permeable filter sock containing calcium oxy-hydroxide based chemical which produces a controlled release of molecular oxygen (17% by weight) when hydrated.
Results
PHC and dry cleaning compounds were reduced in concentrations to groundwater standards following the application of RegenOx and ORC Advanced, facilitating the redevelopment of the former dry cleaning business to house the not-for-profit homeless shelter, Ruth and Naomi’s Mission, serving the Chilliwack, B.C. community. Upon completion of investigation and remedial efforts, the project was awarded three British Columbia Ministry Environment instruments. Up to 200+ homeless are served dinner daily by this organization which provides both shelter and recovery programs to men and women, assisting them in their reintegration into the community and work place.
1 PulseOx is a registered trademark of APT Water, Inc.
ISCO and Enhanced Aerobic Bioremediation during Residential Development
Excavation works minimised through the use of RegenOx, ORC-Advanced and ORC-Advanced Pellets, allowing development to continue without interruption.Read More
Groundwater in Soils and Bedrock Treated at an Industrial Site, Sweden
High concentrations of TCE were found within the soil and groundwater and the contamination had infiltrated the underlying fractured mudstone bedrock…Read More
Pilot Study at Former Gasworks, Southeast England, UK
Pilot study results on a former gasworks site show that within 10 weeks of injecting PetroCleanze and ORC Advanced, significant mass reduction can be achieved. The pilot study is scalable to the entire site. Targeted remediation to reduce the contaminant mass in the most sensitive areas has the potential to dramatically reduce remediation costs for the developer.
REGENESIS Remediation Services’ Efficient ISCO Treatment Keeps Redevelopment Schedule of Former Gas Station On Track
Project Highlights
- Three distinct zones of contamination effectively treated by in situ chemical oxidation (ISCO) and enhanced aerobic bioremediation
- Benzene (BTEX) concentrations in groundwater reduced by >99% within three months, achieving site goals for Low-Threat Closure (LTC)
- The treatment, design and application efficiency provided by REGENESIS® Remediation Services allowed the redevelopment schedule to be maintained
Project Summary
Operations at the site of a former gas station in San Jose, California resulted in contamination of the subsoil and groundwater with benzene. Following demolition of the station after 15 years of operation, the site was approved for redevelopment into a commercial property. However, the site failed to meet the groundwater criteria of the Low-Threat Underground Storage Tank Case Closure Policy (LTCP) for benzene (<3,000 μg/L) concentrations, and remediation activities were quickly undertaken in order to maintain the schedule for site redevelopment.
A remediation plan was developed by REGENESIS® that utilized in situ chemical oxidation and enhanced aerobic biodegradation to address the residual petroleum contamination at the site. Due to the extended drought in the area that caused rapidly declining groundwater levels, three separate zones of contamination were targeted in the remediation plan: the groundwater zone and two newly-formed vadose zones that are separated by a low-permeability unit. The 3700 ft2 treatment area included full coverage by the groundwater treatment as well as two distinct regions of the shallow and deep vadose zones.
A bench test using soil and groundwater from the site was performed to verify the effectiveness of the planned course of treatment prior to full-scale application. A >99% reduction in benzene concentrations confirmed the remediation plan, and application of the remediation chemistry was performed by REGENESIS Remediation Services (RRS) over two injection events. Due to the prolonged drought in the area, recycled water was brought on site for use in the field activities. The two injection events were separated by one month and each spanned ten days. During the first event, PersulfOx® was applied via direct push technology to 54 injection points. In the second event, ORC Advanced® was co-applied with PersulfOx through 59 points.
Technology Description
PersulfOX is a sodium persulfate-based chemical oxidation technology that destroys both hydrocarbon and chlorinated solvent contaminants in the subsurface. PersulfOx contains a built-in catalyst that activates the persulfate component and generates contaminant-destroying free radicals without the need for the addition of a separate activator.
ORC Advanced is a proprietary formulation of food-grade, calcium oxyhydroxide that produces a controlled release of molecular oxygen to enhance aerobic biodegradation.
Results
Three months after treatment of the site was completed, BTEX concentrations decreased by over 99% from the baseline concentrations of 3070 μg/L. Furthermore, concentrations of all contaminants have been reduced to below the criteria for Low Threat Closure, and as a result of this rapid achievement of site goals, the redevelopment schedule of the site has been preserved.
Chlorinated Solvent Remediation via ISCO at Former Industrial Site in Barcelona, Spain
Due to the target area extending under the footprint of the proposed building and the short build programme, a grid of horizontal injection pipes was installed in the subsurface prior to construction commencing. The grid was then linked to a remote injection location, so that when the new building was constructed, injection was simultaneously completed underneath it. The intention of the remediation was to achieve a rapid and significant reduction of the contaminant concentrations in the groundwater. PersulfOx was selected as the preferred ISCO agent due to its efficiency and capability of moving through the vadose zone into the groundwater, guaranteeing a good distribution.Read More
